Dominion isn't that great IMO. It is not as competitive as the Classic (DotA) is. Basically you just roam from one place to another place, capturing points and hoping not to get caught by a group of 3, which is pretty aimless and pointless to me. The sense of achievement you can get from Dominion is nothing comparable to that from Classic. Barely you will participate in a team-fight and every one show their true skills to kill as many champions as they can. As the champion balance is made based of the classic mode, so some champions are just too good in Dominion. If Classic is for competitive game-play with zero tolerance of errors, then Dominion will be for leisure and show greater room for errors.